Non-capsular acidic polysaccharides have been isolated from the cell walls of B meningococci which may allow antigenic segregation of this serogroup. This family of antigens is similar to the Gc antigens of the gonococcus and one population of B meningococcal antigens has been found to be antigenically identical to gonococcal Gc2 antigens. The objectives of this proposal are 1) the delineation of the scope of antigenic variation among group B meningococci using these acidic polysaccharides as a basis, 2) the development of serotyping systems with these polysaccharides, 3) analysis of their immunochemical characteristics, and 4) analysis of their immunogenicity in several animal species. These antigens will be isolated from B meningococcal phenol-water endotoxin by DEAE chromatography after alkaline hydrolysis. The serotyping systems will be developed utilizing HAI methodology. Rabbit immunizations will be performed with whole antigens and isolated antigens. These sera will be tested in precipitin, HA, and bactericidal systems. Studies of the immune response of these antigens in mice will be performed using the plaque assay method.